Product state - Alchetron, The Free Social Encyclopedia

In quantum mechanics, a product state, or simply separable state, is a special type of separable state in which there are neither classical nor quantum correlations. Precisely, it is a joint state of two systems which can be expressed as

ρ = ρ 1 ⊗ ρ 2 ,

where ρ 1 and ρ 2 are states of the respective systems. This is a more restrictive condition than mere separability,

ρ = ∑ k p k ρ 1 k ⊗ ρ 2 k .

One property of the product state is that in terms of entropy,

S ( ρ ) = S ( ρ 1 ) + S ( ρ 2 ) .

References

Product state Wikipedia

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